This invention relates to an improved system for maintaining a positive mesh between certain gears of a type used to translate power from a motor to a wheeled axle.
In the field of toy miniature powered vehicles, it is common to have the motor drive a rigid rear axle through direct gearing. Since the motor is usually located forward of the axle, the motor drive shaft is oriented perpendicular to the axle, so that the gearing must shift the plane of rotation 90.degree.. The gearing usually has a substantial reduction ratio to keep the vehicle speed reasonable given a relatively high motor RPM.
A commonly employed gear system fitting the above requirements comprises a pinion gear on the drive shaft, meshed to a relatively large diameter crown gear on the axle. This combination is simple and inexpensive, both important considerations in view of the low cost nature of the vehicle product, and yet it quite adequately meets the requirements demanded of a gear train for toy vehicles.
A major problem with this gear system lies in maintaining a positive mesh of the crown gear teeth with the pinion gear despite lateral movement of the rear axle. One solution has been to provide a sleeve or spacer on the axle between the frame of the chassis and the crown gear. The sleeve may actually be an integral extension of the crown gear itself. Other possible solutions include collars on the axle on either side of the frame, or a sleeve between the frame and a wheel of the rear axle. However, there are shortcomings in the systems described above. Large contact areas between the sleeves and frame or wheel cause increased frictional drag. They are also susceptible to binding if the frame or axle is slightly bent or if a piece of debris should get wedged between the surfaces. If the frame or axle is significantly bent, the gears may come out of mesh.
The present invention is directed to an improved method of maintaining a positive gear mesh between the motor pinion and axle crown gears.